Effects of Personal Exposure to Ambient Fine Particulate Matter on Acute Change in Nocturnal Heart Rate Variability in Subjects Without Overt Heart Disease

Neural mechanism facilitating PM2.5-related cardiac arrhythmias through cardiovascular autonomic and calcium dysregulation in a rat model

Particulate matter < 2.5 μm (PM2.5) exposure is associated with increased arrhythmia events and cardiovascular mortality, but the detailed mechanism remained elusive. In the current study, we aimed to investigate the autonomic alterations in a rodent model after acute exposure to PM2.5. Twelve male WKY rats were randomized to control and PM2.5 groups. All were treated with 2 exposures of oropharyngeal aerosol inhalations (1 μg PM2.5 per gram of body weight in 100 μL normal saline for the PM2.5 group) separately by 7 days. Polysomnography and electrocardiography were surgically installed 7 days before oropharyngeal inhalation and monitored for 7 days after each inhalation. Physiologic monitors were used to define active waking (AW), quiet sleep (QS), and paradoxical sleep (PS). Autonomic regulations were measured by heart rate variability (HRV). The protein expression of ventricular tissue of the 2 groups was compared at the end of the experiment. In sleep pattern analysis, QS interruption of the PM2.5 group was significantly higher than the control group (0.52 ± 0.13 events/min, 0.35 ± 0.10 events/min, p = 0.002). In HRV analysis, the LF/HF was significantly higher for the PM2.5 group than the control group (1.15 ± 0.16, 0.64± 0.30, p = 0.003), largely driven by LF/HF increase during the QS phase. Ionic channel protein expression from Western blots showed that the PM2.5 group had significantly lower L-type calcium channel and higher SERCA2 and rectifier potassium channel expressions than the control group, respectively. Our results showed that acute PM2.5 exposure leads to interruption of QS, sympathetic activation, and recruitment of compensatory calcium handling proteins. The autonomic and calcium dysregulations developed after PM 2.5 exposure may explain the risk of sleep disturbance and sleep-related arrhythmia.

Wearable Sensor-Based Monitoring of Environmental Exposures and the Associated Health Effects: A Review

Recent advances in sensor technology have facilitated the development and use of personalized sensors in monitoring environmental factors and the associated health effects. No studies have reviewed the research advancement in examining population-based health responses to environmental exposure via portable sensors/instruments. This study aims to review studies that use portable sensors to measure environmental factors and health responses while exploring the environmental effects on health. With a thorough literature review using two major English databases (Web of Science and PubMed), 24 eligible studies were included and analyzed out of 16,751 total records. The 24 studies include 5 on physical factors, 19 on chemical factors, and none on biological factors. The results show that particles were the most considered environmental factor among all of the physical, chemical, and biological factors, followed by total volatile organic compounds and carbon monoxide. Heart rate and heart rate variability were the most considered health indicators among all cardiopulmonary outcomes, followed by respiratory function. The studies mostly had a sample size of fewer than 100 participants and a study period of less than a week due to the challenges in accessing low-cost, small, and light wearable sensors. This review guides future sensor-based environmental health studies on project design and sensor selection.

Redox Regulatory Changes of Circadian Rhythm by the Environmental Risk Factors Traffic Noise and Air Pollution

Significance: Risk factors in the environment such as air pollution and traffic noise contribute to the development of chronic noncommunicable diseases. Recent Advances: Epidemiological data suggest that air pollution and traffic noise are associated with a higher risk for cardiovascular, metabolic, and mental disease, including hypertension, heart failure, myocardial infarction, diabetes, arrhythmia, stroke, neurodegeneration, depression, and anxiety disorders, mainly by activation of stress hormone signaling, inflammation, and oxidative stress. Critical Issues: We here provide an in-depth review on the impact of the environmental risk factors air pollution and traffic noise exposure (components of the external exposome) on cardiovascular health, with special emphasis on the role of environmentally triggered oxidative stress and dysregulation of the circadian clock. Also, a general introduction on the contribution of circadian rhythms to cardiovascular health and disease as well as a detailed mechanistic discussion of redox regulatory pathways of the circadian clock system is provided. Future Directions: Finally, we discuss the potential of preventive strategies or "chrono" therapy for cardioprotection. Antioxid. Redox Signal. 37, 679-703.

Acute effects of short-term exposure to ambient air pollution on reproductive hormones in young males of the MARHCS study in China

Air pollution, which is associated with male reproductive health. However, it is unknown the acute effects of ambient air pollutants exposure on male reproductive hormones. The current study, we measured serum levels of reproductive hormone in 2030 blood samples gathered from The Male Reproductive Health in Chongqing College Students (MARHCS) cohort study. We derived a full coverage of ambient air pollutant (PM₁₀, PM_2.5, SO₂, NO₂, CO and O₃) concentrations by employing machine learning algorithms, and used a mixed-effect model to estimate single-day and cumulative effects of air pollutants exposure on serum reproductive hormones. Our results showed that (1) PM₁₀ and PM_2.5 concentrations were positively associated with estradiol (E₂) in both single and cumulative lag days, but were negatively associated with the ratio of Testosterone/E₂ (the T/E₂ ratio). NO₂ was positively associated with estradiol at lag day 2 (95% CI: 0.290, 0.881; corrected P = 0.048) and lag 0-2 days (95% CI: 0.523, 1.337; corrected P = 0.003), with progesterone (P) at lag day 2 and lag day 3 (corrected P < 0.05). There was also a positive association between CO exposure and progesterone at lag day 2. (2) SO₂ was inversely associated with E₂ at lag day 3, 4 and lag 0-4 days, and progesterone at lag day 0, 1, 2 and lag 0-1, 0-2, 0-4 days, but positively associated with the T/E₂ ratio at lag day 3, 4 and lag 0-4 days (corrected P < 0.05). O₃ exposure was negatively associated with E₂ at lag day 3 (95% CI: -0.216, -0.074, corrected P = 0.03). (3) No significant associations were found between the cumulative daily average air pollutant exposure of CO, O₃ and hormone outcomes. This study suggests that short-term exposure to air pollutants may thus alter reproductive hormone levels, especially on serum estradiol, progesterone levels and the T/E₂ ratio.

A community-based study on associations between PM2.5 and PM1 exposure and heart rate variability using wearable low-cost sensing devices

Few studies have investigated the effect of personal PM_2.5 and PM₁ exposures on heart rate variability (HRV) for a community-based population, especially in Asia. This study evaluates the effects of personal PM_2.5 and PM₁ exposure on HRV during two seasons for 35 healthy adults living in an urban community in Taiwan. The low-cost sensing (LCS) devices were used to monitor the PM levels and HRV, respectively, for two consecutive days. The mean PM_2.5 and PM₁ concentrations were 13.7 ± 11.4 and 12.7 ± 10.5 μg/m³ (mean ± standard deviation), respectively. Incense burning was the source that contributed most to the PM_2.5 and PM₁ concentrations, around 9.2 μg/m³, while environmental tobacco smoke exposure had the greatest impacts on HRV indices, being associated with the highest decrease of 20.2% for high-frequency power (HF). The results indicate that an increase in PM_2.5 concentrations of one interquartile range (8.7 μg/m³) was associated with a change of -1.92% in HF and 1.60% in ratio of LF to HF power (LF/HF). Impacts on HRV for PM₁ were similar to those for PM_2.5. An increase in PM₁ concentrations of one interquartile range (8.7 μg/m³) was associated with a change of -0.645% in SDNN, -1.82% in HF and 1.54% in LF/HF. Stronger immediate and lag effects of PM_2.5 exposure on HRV were observed in overweight/obese subjects (body mass index (BMI) ≥24 kg/m²) compared to the normal-weight group (BMI <24 kg/m²). These results indicate that even low-level PM concentrations can still cause changes in HRV, especially for the overweight/obese population.

Response of the Cardiac Autonomic Control to Exposure to Nanoparticles and Noise: A Cross-Sectional Study of Airport Ground Staff

Airport activity causes the emission of particulate matter and noise, two environmental contaminants and potential health hazards, particularly for the personnel operating nearby taxiways. We explored the association between exposure to fine/ultrafine particles (UFPs) and noise with heart rate variability (HRV), an early indicator of cardiovascular autonomic response, among a sample of airport ground staff. Between May and June 2018, thirty-four male operators (mean age = 43 years and SD = 6.7) underwent personal monitoring of exposure to nanoparticles and noise, and HRV during their work activity. We conducted univariate and multivariate analysis to test the effect of UFP and noise exposure HRV. Total Lung Deposition Surface Area (LDSA) was significantly associated with a decrease in HRV Total Power and Triangular index (β = -0.038 p = 0.016 and β = -7.8 × 10-5, p = 0.042, respectively). Noise peak level showed an opposite effect, which was significant for Total Power (β = 153.03, p = 0.027), and for Triangular index (β = 0.362, p = 0.035). Further investigation is warranted to clarify the effect of the concurrent exposure to UFPs and noise on early changes of cardiac autonomic regulation.

Acute effect of ambient fine particulate matter on heart rate variability: an updated systematic review and meta-analysis of panel studies

Background

Decreased heart rate variability (HRV) is a predictor of autonomic system dysfunction, and is considered as a potential mechanism of increased risk of cardiovascular disease (CVD) induced by exposure to particulate matter less than 2.5 μm in diameter (PM_2.5). Previous studies have suggested that exposure to PM_2.5 may lead to decreased HRV levels, but the results remain inconsistent.

Methods

An updated systematic review and meta-analysis of panel studies till November 1, 2019 was conducted to evaluate the acute effect of exposure to ambient PM_2.5 on HRV. We searched electronic databases (PubMed, Web of Science, and Embase) to identify panel studies reporting the associations between exposure to PM_2.5 and the four indicators of HRV (standard deviation of all normal-to-normal intervals (SDNN), root mean square of successive differences in adjacent normal-to-normal intervals (rMSSD), high frequency power (HF), and low frequency power (LF)). Random-effects model was used to calculate the pooled effect estimates.

Results

A total of 33 panel studies were included in our meta-analysis, with 16 studies conducted in North America, 12 studies in Asia, and 5 studies in Europe. The pooled results showed a 10 μg/m³ increase in PM_2.5 exposure which was significantly associated with a − 0.92% change in SDNN (95% confidence intervals (95%CI) − 1.26%, − 0.59%), − 1.47% change in rMSSD (95%CI − 2.17%, − 0.77%), − 2.17% change in HF (95%CI − 3.24%, − 1.10%), and − 1.52% change in LF (95%CI − 2.50%, − 0.54%), respectively. Overall, subgroup analysis suggested that short-term exposure to PM_2.5 was associated with lower HRV levels in Asians, healthy population, and those aged ≥ 40 years.

Conclusion

Short-term exposure to PM_2.5 was associated with decreased HRV levels. Future studies are warranted to clarity the exact mechanism of exposure to PM_2.5 on the cardiovascular system through disturbance of autonomic nervous function.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12199-020-00912-2.

Acute cardiovascular health effects in a panel study of personal exposure to traffic-related air pollutants and noise in Toronto, Canada

Urban populations are often simultaneously exposed to air pollution and environmental noise, which are independently associated with cardiovascular disease. Few studies have examined acute physiologic responses to both air and noise pollution using personal exposure measures. We conducted a repeated measures panel study of air pollution and noise in 46 non-smoking adults in Toronto, Canada. Data were analyzed using linear mixed-effects models and weighted cumulative exposure modeling of recent exposure. We examined acute changes in cardiovascular health effects of personal (ultrafine particles, black carbon) and regional (PM_2.5, NO₂, O₃, O_x) measurements of air pollution and the role of personal noise exposure as a confounder of these associations. We observed adverse changes in subclinical cardiovascular outcomes in response to both air pollution and noise, including changes in endothelial function and heart rate variability (HRV). Our findings show that personal noise exposures can confound associations for air pollutants, particularly with HRV, and that impacts of air pollution and noise on HRV occur soon after exposure. Thus, both noise and air pollution have a measurable impact on cardiovascular physiology. Noise should be considered alongside air pollution in future studies to elucidate the combined impacts of these exposures in urban environments.

Transient risk of ambient fine particulate matter on hourly cardiovascular events in Tainan City, Taiwan

BACKGROUND

The association between daily changes in ambient fine particulate matter (PM2.5) and cardiovascular diseases have been well established in mechanistic, epidemiologic and exposure studies. Only a few studies examined the effect of hourly variations in air pollution on triggering cardiovascular events. Whether the current PM2.5 standards can protect vulnerable individuals with chronic cardiovascular diseases remain uncertain.

METHODS

we conducted a time-stratified, case-crossover study to assess the associations between hourly changes in PM2.5 levels and the vascular disease onset in residents of Tainan City, Taiwan, visiting Emergency Room of Chi Mei Medical Center between January 2006 and December 2016. There were 26,749 cases including 10,310 females (38.5%) and 16,439 males (61.5%) identified. The time of emergency visit was identified as the onset for each case and control cases were selected as the same times on other days, on the same day of the week in the same month and year respectively. Residential address was used to identify the ambient air pollution exposure concentrations from the closest station. Conditional logistic regression with the stepwise selection method was used to estimate adjusted odds ratios (ORs) for the association.

RESULTS

When we only included cases occurring at PM2.5>10 μg/m3 and PM2.5>25 μg/m3, very significant ORs could be observed for 10 μg/m3 increases in PM2.5 at 0 and 1 hour, implying fine particulate exposure could promptly trigger vascular disease events. Moreover, a very clear increase in risk could be observed with cumulative exposure from 0 to 48 hours, especially in those cases where PM2.5>25 μg/m3.

CONCLUSIONS

Our study demonstrated that transient and low concentrations of ambient PM2.5 trigger adult vascular disease events, especially cerebrovascular disease, regardless of age, sex, and exposure timing. Warning and delivery systems should be setup to protect people from these prompt adverse health impacts.

Metabolomics analysis of urine from healthy wild type mice exposed to ambient PM2.5

BACKGROUND

Ambient fine particulate matter (PM_2.5) exposure has been linked with various adverse health outcomes. However, the urine metabolomics changes impacted by PM_2.5 have not been well elucidated.

METHODS

The normal healthy C57BL/6 mice were exposed to concentrated ambient PM_2.5 (PM) or filtered air (FA) for four weeks using "Shanghai-METAS". The urinary metabolome was quantified using liquid/gas chromatography coupled with mass spectrometry.

RESULTS

There were 2213 metabolites identified in total and 163 of them were significantly different between FA- and PM-exposed mice. The KEGG pathway analysis suggested that there were nine perturbed metabolic pathways related to amino acid metabolism. The amino acid metabolism what mainly impacted by PM_2.5 were beta-alanine, arginine, proline, alanine, aspartate, glutamate, phenylalanine, glycine, serine, threonine and tyrosine metabolism. Meanwhile, nineteen differential metabolites related to lipid metabolism and seven differential metabolites related to glucose homeostasis were different between FA and PM mice. Furthermore, the glucose and its metabolites were significantly increased in the PM mice compared with the FA mice.

CONCLUSION

The current study provided a critical information on evaluating the systemic toxicity of PM_2.5. The results demonstrated that there were significant alterations in urine metabolome by short-term exposure to PM, including amino acid metabolism, lipid metabolism and glucose metabolism. The metabolomics approach might be an effective tool to evaluate the potential mechanism of PM_2.5 in inducing adverse health outcomes.

Influence of mental stress and environmental toxins on circadian clocks: Implications for redox regulation of the heart and cardioprotection

Risk factors in the environment such as air pollution and mental stress contribute to the development of chronic non-communicable disease. Air pollution was identified as the leading health risk factor in the physical environment, followed by water pollution, soil pollution/heavy metals/chemicals and occupational exposures, however neglecting the non-chemical environmental health risk factors (e.g. mental stress and noise). Epidemiological data suggest that environmental risk factors are associated with higher risk for cardiovascular, metabolic and mental diseases, including hypertension, heart failure, myocardial infarction, diabetes, arrhythmia, stroke, depression and anxiety disorders. We provide an overview on the impact of the external exposome comprising risk factors/exposures on cardiovascular health with a focus on dysregulation of stress hormones, mitochondrial function, redox balance and inflammation with special emphasis on the circadian clock. Finally, we assess the impact of circadian clock dysregulation on cardiovascular health and the potential of environment-specific preventive strategies or "chrono" therapy for cardioprotection. LINKED ARTICLES: This article is part of a themed issue on Risk factors, comorbidities, and comedications in cardioprotection. To view the other articles in this section visit http://onlinelibrary.wiley.com/doi/10.1111/bph.v177.23/issuetoc.

Effects of Personal Exposures to Micro- and Nano-Particulate Matter, Black Carbon, Particle-Bound Polycyclic Aromatic Hydrocarbons, and Carbon Monoxide on Heart Rate Variability in a Panel of Healthy Older Subjects

As a non-invasive method, heart rate variability (HRV) has been widely used to study cardiovascular autonomous control. Environmental epidemiological studies indicated that the increase in an average concentration of particulate matter (PM) would result in a decrease in HRV, which was related to the increase of cardiovascular mortality in patients with myocardial infarction and the general population. With rapid economic and social development in Asia, how air pollutants, such as PM of different sizes and their components, affect the cardiovascular health of older people, still need to be further explored. The current study includes a 72 h personal exposure monitoring of seven healthy older people who lived in the Taipei metropolitan area. Mobile equipment, a portable electrocardiogram recorder, and the generalized additive mixed model (GAMM) were adopted to evaluate how HRV indices were affected by size-fractionated PM, particle-bound polycyclic aromatic hydrocarbons (p-PAHs), black carbon (BC), and carbon monoxide (CO). Other related confounding factors, such as age, sex, body mass index (BMI), temperature, relative humidity (RH), time, and monitoring week were controlled by fixed effects of the GAMM. Statistical analyses of multi-pollutant models showed that PM_2.5–10, PM₁, and nanoparticle (NP) could cause heart rate (HR), time-domain indices, and frequency-domain indices to rise; PM_1–2.5 and BC would cause the frequency-domain index to rise; p-PAHs would cause HR to rise, and CO would cause time-domain index and frequency-domain index to decline. In addition, the moving average time all fell after one hour and might appear at 8 h in HRVs’ largest percentage change caused by each pollutant, results of which suggested that size-fractionated PM, p-PAHs, BC, and CO exposures have delayed effects on HRVs. In conclusion, the results of the study showed that the increase in personal pollutant exposure would affect cardiac autonomic control function of healthy older residents in metropolitan areas, and the susceptibility of cardiovascular effects was higher than that of healthy young people. Since the small sample size would limit the generalizability of this study, more studies with larger scale are warranted to better understand the HRV effects of simultaneous PM and other pollution exposures for subpopulation groups.

Impacts of In-Cabin Exposure to Size-Fractionated Particulate Matters and Carbon Monoxide on Changes in Heart Rate Variability for Healthy Public Transit Commuters

To evaluate the cardiovascular impact of traffic-related pollutant exposure on healthy young adults, the research team has collected the primary data of in-cabin exposure to air pollutants and heart rate variability (HRV). Twenty young healthy college students were recruited in Taipei metropolitan area. In addition to electrocardiogram, personal exposure to air pollutants, i.e., particulate matter (PM) and carbon monoxide (CO), and weather conditions, including temperature and relative humidity (RH), on campus, bus, and mass rapid transit were monitored continuously. The following HRV parameters were evaluated using generalized additive mixed model to adjust for personal and meteorological variables: heart rate (HR), the square root of the mean of the sum of the squares of differences between adjacent normal-to-normal (NN) intervals (r-MSSD), the standard deviation of all NN intervals (SDNN), the percentage of successive NN interval differences greater than 50 ms (pNN50), low-frequency power (LF), high-frequency power (HF), total power (TP), and LF/HF. They were assessed to find out the association between in-cabin exposure and HRV parameters. Compared with the HRV parameters measured on campus, the percent changes in r-MSSD, SDNN, pNN50+1, LF, HF, and TP decreased when the participants were in public transits. After adjusting for all locations, 5 min moving averages of PM2.5–10 and PM1 were significantly associated with the increase in the percent changes in HR and SDNN. Additionally, 5 min moving averages of PM2.5–10 exposure were significantly associated with the decrease in the percent change in HF, while it was significantly associated with the increase of the percent change in LF/HF. The reduction of the percent change in HR was also found to be significantly associated with 5 min CO moving averages. To conclude, current analyses have shown that size-fractionated PMs and CO exposure in public transits might lead to significant changes of HRV parameters for healthy young adults.

Acute Effects of Air Pollution and Noise from Road Traffic in a Panel of Young Healthy Adults

Panel studies are an efficient means to assess short-term effects of air pollution and other time-varying environmental exposures. Repeated examinations of volunteers allow for an in-depth analysis of physiological responses supporting the biological interpretation of environmental impacts. Twenty-four healthy students walked for 1 h at a minimum of four separate occasions under each of the following four settings: along a busy road, along a busy road wearing ear plugs, in a park, and in a park but exposed to traffic noise (65 dB) through headphones. Particle mass (PM_2.5, PM₁), particle number, and noise levels were measured throughout each walk. Lung function and exhaled nitrogen oxide (NO) were measured before, immediately after, 1 h after, and approximately 24 h after each walk. Blood pressure and heart rate variability were measured every 15 min during each walk. Recorded air pollution levels were found to correlate with reduced lung function. The effects were clearly significant for end-expiratory flows and remained visible up to 24 h after exposure. While immediate increases in airway resistance could be interpreted as protective (muscular) responses to particulate air pollution, the persisting effects indicate an induced inflammatory reaction. Noise levels reduced systolic blood pressure and heart rate variability. Maybe due to the small sample size, no effects were visible per specific setting (road vs. park).

Cardiac Autonomic Effects of Secondhand Exposure to Nicotine from Electronic Cigarettes: An Exploratory Study

Background

The rapid increase in prevalence of e-cigarette (EC) use may lead to widespread exposure to secondhand emissions among nonsmokers, but evidence on the potential cardiovascular health risks is limited. We aimed to investigate effect of short-term secondhand exposure to nicotine from e-cigarette (EC) emissions on cardiac autonomic function using heart rate variability (HRV).

Methods

A randomized, repeated measures crossover study of healthy nonsmoking volunteers was conducted. Standard deviation of NN intervals (SDNN), average of the standard deviation of NN intervals (ASDNN), root mean square of successive differences (rMSSD), and heart rate-corrected QT interval (QTc) were calculated during one hour of EC exposure session.

Results

Nicotine from EC emissions was associated with a 7.8% decrease in SDNN (95% CI, -11.2% to -4.3%), 7.7% decrease in ASDNN (95% CI, -11.0% to -4.2%) and 3.8 msec decrease in QTc (95% CI, -5.8 to -1.9). Compared with a short exposure time period (<15min), greater nicotine associated with reductions in ASDNN (P _{for interaction} = 0.076) with longer exposure time periods. For QTc, greater nicotine associated with reductions were found during 15-30 min exposure time period (P _{for interaction} = 0.04).

Conclusion

We present the first evidence of cardiac autonomic effects of short-term secondhand exposure to nicotine from EC emissions among healthy nonsmokers. Further comprehensive research on EC exposure extending to more subjects and flavor compounds is warranted.

Characterization of a High PM2.5 Exposure Group in Seoul Using the Korea Simulation Exposure Model for PM2.5 (KoSEM-PM) Based on Time⁻Activity Patterns and Microenvironmental Measurements

The Korea Simulation Exposure Model for fine particulate matter (PM_2.5) (KoSEM-PM) was developed to estimate population PM_2.5 exposure in Korea. The data were acquired based on 59,945 min of the actual microenvironmental PM_2.5 measurements and on the time–activity patterns of 8072 residents of Seoul. The aims of the study were to estimate daily PM_2.5 exposure of Seoul population, and to determine the characteristics of a high exposure group. KoSEM-PM estimated population exposures by applying the PM_2.5 distribution to the matching time–activity patterns at 10-min intervals. The mean personal PM_2.5 exposure level of the surveyed subjects in Seoul was 26.0 ± 2.7 µg/m³ (range: 21.0–40.2 µg/m³) in summer. Factors significantly associated with high exposure included day of the week, age, industry sector, job type, and working hours. Individuals surveyed on Saturdays were more likely to be in the high exposure group than those surveyed on weekdays and Sundays. Younger, non-office-working individuals with longer working hours were more likely to be in the high exposure group. KoSEM-PM could be a useful tool to estimate population exposure levels to other region in Korea; to expand its use, microenvironmental measurements are required for other region in Korea.

Effects of Personal Short-Term Exposure to Ambient Ozone on Blood Pressure and Vascular Endothelial Function: A Mechanistic Study Based on DNA Methylation and Metabolomics

Short-term exposure to ambient ozone is associated with adverse cardiovascular effects, with inconsistent evidence on the molecular mechanisms. We conducted a longitudinal panel study among 43 college students in Shanghai to explore the effects of personal ozone exposure on blood pressure (BP), vascular endothelial function, and the potential molecular mechanisms. We measured real-time personal ozone exposure levels, serum angiotensin-converting enzyme (ACE) and endothelin-1 (ET-1), and locus-specific DNA methylation of ACE and EDN1 (coding ET-1). We used an untargeted metabolomic approach to explore potentially important metabolites. We applied linear mixed-effect models to examine the effects of ozone on the above biomarkers. An increase in 2 h-average ozone exposure was significantly associated with elevated levels of BP, ACE, and ET-1. ACE and EDN1 methylation decreased with ozone exposure, but the magnitude differed by genomic loci. Metabolomics analysis showed significant changes in serum lipid metabolites following ozone exposure that are involved in maintaining vascular endothelial function. Our findings suggested that acute exposure to ambient ozone can elevate serum levels of ACE and ET-1, decrease their DNA methylation, and alter the lipid metabolism, which may be partly responsible for the effects of ozone on BP and vascular endothelial function.

Cytotoxicity of Air Pollutant 9,10-Phenanthrenequinone: Role of Reactive Oxygen Species and Redox Signaling

Atmospheric pollution has been a principal topic recently in the scientific and political community due to its role and impact on human and ecological health. 9,10-phenanthrenequinone (9,10-PQ) is a quinone molecule found in air pollution abundantly in the diesel exhaust particles (DEP). This compound has studied extensively and has been shown to develop cytotoxic effects both in vitro and in vivo. 9, 10-PQ has been proposed to play a critical role in the development of cytotoxicity via generation of reactive oxygen species (ROS) through redox cycling. This compound also reduces expression of glutathione (GSH), which is critical in Phase II detoxification reactions. Understanding the underlying cellular mechanisms involved in cytotoxicity can allow for the development of therapeutics designed to target specific molecules significantly involved in the 9,10-PQ-induced ROS toxicity. This review highlights the developments in the understanding of the cytotoxic effects of 9, 10-PQ with special emphasis on the possible mechanisms involved.

Acute particulate matter affects cardiovascular autonomic modulation and IFN-γ methylation in healthy volunteers

AIMS

Air particulate matter (PM) is associated with increased cardiovascular morbidity and mortality. Altered autonomic functions play a key role in PM-induced cardiovascular disease. However, previous studies have not address the impact of PM on sympathetic and parasympathetic control of heart function, independently, and using controlled conditions, i.e., increasing titration of PM of known composition, in absence of other potential confounding factors. To fill this gap, here we used symbolic analysis that is capable of detecting non-mutual changes of the two autonomic branches, thus considering them as independent, and concentrations of PM as they could be measured at peak levels in Milan during a polluted winter day.

METHODS AND RESULTS

In this randomized, cross-over study, we enrolled 12 healthy subjects who underwent two random sessions: inhalation of filtered air mixture or inhalation of filtered air containing particulate mixture (PM 10, PM 2.5, PM 1.0 and PM 0.5µm). ECG and respiration for autonomic analysis and blood sample for DNA Methylation were collected at baseline (T1), after air exposure (T2) and after 2h (T3). Spectral and symbolic analysis of heart rate variability (HRV) were performed for autonomic control of cardiac function, while alterations in DNA methylation of candidate genes were used to index pro-inflammatory modifications. In the PM expose group, autonomic analysis revealed a significant decrease of 2UV%, index of parasympathetic modulation (14% vs 9%, p = 0.0309), while DNA analysis showed a significant increase of interferon γ (IFN- γ) methylation, from T1 to T3. In a mixed model using T1, T2 and T3, fine and ultrafine PM fractions showed significant associations with IFN- γ methylation and parasympathetic modulation.

CONCLUSIONS

Our study shows, for the first time, that in healthy subjects, acute exposure to PM affects parasympathetic control of heart function and it increases methylation of a pro-inflammatory gene (i.e. methylation of interferon γ). Thus, our study suggests that, even in absence of other co-factors and in otherwise healthy individuals, PM per se is sufficient to trigger parasympathetic dysautonomia, independently from changes in sympathetic control, and inflammation, in a dose-dependent manner.

Particulate Matter Exposure and Stress Hormone Levels

Background:

Exposure to ambient particulate matter (PM) is associated with a number of adverse health outcomes, but potential mechanisms are largely unknown. Metabolomics represents a powerful approach to study global metabolic changes in response to environmental exposures. We therefore conducted this study to investigate changes in serum metabolites in response to the reduction of PM exposure among healthy college students.

Methods:

We conducted a randomized, double-blind crossover trial in 55 healthy college students in Shanghai, China. Real and sham air purifiers were placed in participants’ dormitories in random order for 9 days with a 12-day washout period. Serum metabolites were quantified by using gas chromatography-mass spectrometry and ultrahigh performance liquid chromatography-mass spectrometry. Between-treatment differences in metabolites were examined using orthogonal partial least square-discriminant analysis and mixed-effect models. Secondary outcomes include blood pressure, corticotropin-releasing hormone, adrenocorticotropic hormone, insulin resistance, and biomarkers of oxidative stress and inflammation.

Results:

The average personal exposure to PMs with aerodynamic diameters ≤2.5 μm was 24.3 μg/m 3 during the real purification and 53.1 μg/m 3 during the sham purification. Metabolomics analysis showed that higher exposure to PMs with aerodynamic diameters ≤2.5 μm led to significant increases in cortisol, cortisone, epinephrine, and norepinephrine. Between-treatment differences were also observed for glucose, amino acids, fatty acids, and lipids. We found significantly higher blood pressure, hormones, insulin resistance, and biomarkers of oxidative stress and inflammation among individuals exposed to higher PMs with aerodynamic diameters ≤2.5 μm.

Conclusions:

This study suggests that higher PM may induce metabolic alterations that are consistent with activations of the hypothalamus-pituitary-adrenal and sympathetic-adrenal-medullary axes, adding potential mechanistic insights into the adverse health outcomes associated with PM. Furthermore, our study demonstrated short-term reductions in stress hormone following indoor air purification.

Clinical Trial Registration:

URL: http://www.clinicaltrials.gov . Unique identifier: NCT02712333.

Impact assessment of PM10 cement plants emissions on urban air quality using the SCIPUFF dispersion model

The Second-order Closure Integrated Puff (SCIPUFF) model was used to study the impact on urban air quality caused by two cement plants emissions located near the city of Caserta, Italy, during the entire year of 2015. The simulated and observed PM10 concentrations were compared using three monitoring stations located in urban and sub-urban area of Caserta city. Both simulated and observed concentrations are shown to be highest in winter, lower in autumn and spring and lowest in summer. Model results generally follow the pattern of the observed concentrations but have a systematic under-prediction of the concentration values. Measures of the bias, NMSE and RMSE indicate a good correlation between observed and estimated values. The SCIPUFF model data analysis suggest that the cement plants are major sources for the measured PM10 values and are responsible for the deterioration of the urban air quality in the city of Caserta.

Traffic-related air pollution is associated with cardio-metabolic biomarkers in general residents

PURPOSE

The study was conducted to explore the mechanisms linking traffic-related air pollution and cardio-metabolic risk.

METHODS

The participants included 371 men and women aged from 45 to 75 in an urban residential area in Shanghai, China. The participants were divided into four categories (≤50, 51-100, 101-200 and >200 m) according to the residential distance to major road. Additionally, the personal fine particulate matter (PM2.5) was measured from 8:00 am to 6:00 pm to assess the PM2.5 exposure in general residents. Then, the continuous subclinical measurements and biological effects related to cardio-metabolic disorders were detected. The generalized linear regression analysis was applied for estimating the adjusted hazards ratio for cardio-metabolic disorders relative to traffic-related air pollution.

RESULTS

The average personal PM2.5 is 111.1 μg/m(3) in the participants living within 50 m to major road, which is significantly higher than the personal PM2.5 (68.2 μg/m(3)) in the participants living more than 200 m away from the major road. The participants living within 50 m to major road compared with those living more than 200 m away have 1.15 times higher of heart rate (HR), 1.95 times higher of fasting insulin, 1.30 times higher of homeostasis model assessment of insulin resistance (HOMA-IR), 1.56 times higher of low-density lipoprotein cholesterol (LDL-C), 8.39 times higher of interleukin 6 (IL-6), 4.30 times higher of augmentation index (AI), 1.60 times higher of systolic blood pressure (SBP) and 1.91 times higher of diastolic blood pressure (DBP). Contrary to the increase in above biological effects, there were 1.06 times lower of low frequency (LF), 1.05 times lower of high frequency (HF), 2.54 times lower of IL-10, 4.61 times lower of nitric oxide (NO), 1.19 times lower of superoxide dismutase (SOD) and 1.85 times lower of total antioxidant capacity (T-AOC). There was no clear exposure-response relationship can be observed in the fasting glucose, LF/HF, cholesterol and high-density lipoprotein (HDL).

CONCLUSION

Long-term exposure to traffic-related air pollution may contribute to the development or exacerbation of cardio-metabolic disorders. The mechanisms linking air pollution and cardio-metabolic disorders may be associated with the increased systemic inflammation and oxidative stress, reduced insulin sensitivity and elevated arterial stiffness and blood pressure.